In terms of whole numbers, Los Angeles saw the West's greatest population gain between 2010 and 2011, of 27,077, Thomas reports. But L.A. is so large already that the increase amounted to just a 0.71 percent population gain.

Denver now ranks seventh among the West's cities in population within city limits, according to Thomas' numbers, behind L.A. (3,819,702), Phoenix (1,469,471), San Diego (1,326,179), San Jose (967,487), San Francisco (812,826) and Seattle (620,778).